Milwaukee Mayor Tom Barrett, the presumptive Democratic nominee for governor of Wisconsin, has a new TV ad highlighting an important story from last year: When Barrett was violently assaulted in August 2009, after intervening in an altercation at the state fair.

Barrett stepped in to defend a woman who was trying to protect her 1-year-old granddaughter from the girl's drunk father. The man then attacked Barrett, beating him in the head and hand with a tire iron. (Barrett did not personally know the individuals involved, his campaign confirmed to us.) Barrett was hospitalized and has undergone multiple operations on his hand, which doctors say might never fully recover. The assailant was later sentenced to 12 years in prison.

The ad shows Barrett's wife Kris talking about how she was out of town when the incident happened, and got a phone call telling her about it. The ad then cuts to news clips about the incident -- and also shows a photo of the severely injured face of Barrett in the hospital at the time. "I know, and our kids know, that their dad will always stand up for them," says Kris Barrett. "And he will always stand up for Wisconsin."

I asked Barrett campaign communications director Phil Walzak whether the ad was in any way intended to be a response to an ad from one of the Republican candidates, Milwaukee County Executive Scott Walker, in which Walker donned boxing gloves and said he would take on Barrett and the Democratic political machine. "No, it's not," said Walzak.

"What Tom has said is this was an important moment in his life and the life of his family," Walzak explained, "and he thought it important to share, as all voters are entitled to know about the candidate, and the people can decide for themselves what it means in the race for governor."

The TPM Poll Averages show Walker leading Barrett by 49.0%-42.9%, and Republican former Congressman Mark Neumann leading Barrett by 45.9%-43.4%. The Republican primary will be held this coming Tuesday.

(Full disclosure: I was a volunteer back in 2002 for Barrett's first gubernatorial campaign, in the Democratic primary. I have not had any additional political involvement with him since that time.)